12 Quality Contro In broad terms, the quality control staff, under the supervision of a qualified food chemist, should be respons ible for the following (1)The evaluation of quality of all incoming raw material, supplementary ingredients used in processing, chemicals, packaging material, cellulose and other film, paper and fibreboard containers, and certain consumable stores 2)All routine laboratory tests on raw material, finished products, lye and blancher liquor, boiler and processing water; (3)Sampling procedures (4)Recording processing data, ie, drying temperatures, peeling and blanching procedures, cooking records for precooked products, such as meats, etc (5)Research and development work on new products, packaging and processing methods (6) Logging of complaints from consumers, and pursuing these to origin and eliminating the cause (7) Supervision of methods of plant cleaning and sanitation, and establishing firm principles of hygiene for personnel and plant maintenance; ( 8)Arrangements for and supervision of pest and rodent control by contractors primarily concerned in these duties (9)Liaison at all times with production management
12 Quality Control In broad terms, the quality control staff, under the supervision of a qualified food chemist, should be responsible for the following: (1) The evaluation of quality of all incoming raw material, supplementary ingredients used in processing, chemicals, packaging material, cellulose and other film, paper and fibreboard containers, and certain consumable stores: (2) All routine laboratory tests on raw material, finished products, lye and blancher liquor, boiler and processing water; (3) Sampling procedures; (4) Recording processing data, ie, drying temperatures, peeling and blanching procedures, cooking records for precooked products, such as meats, etc; (5) Research and development work on new products, packaging and processing methods; (6) Logging of complaints from consumers, and pursuing these to origin and eliminating the cause; (7) Supervision of methods of plant cleaning and sanitation, and establishing firm principles of hygiene for personnel and plant maintenance; (8) Arrangements for and supervision of pest and rodent control by contractors primarily concerned in these duties; (9) Liaison at all times with production management. 233
LABORATORY ANALYTICAL TESTS Rs aving received samples representative of a batch of finished product, or coming raw material, the staff will carry out the following tests Moisture For moisture tests, either a vacuum oven, set at 70'C, or a fan assisted air oven set at 100-103.C, is used. The former is more accurate, albeit slower, on account of the low temperature used, as this prevents the charring and burning of the sample when it is completely dried out, and allows a more exact result to be calculated Samples of raw vegetable should be grated finely before testing, and dry products should be ground in a small coffee grinder The sample material is dried down to zero moisture, and th weight expressed as a percentage of the original to the nearest 0. 1 percent. Two hours is the average time for drying down most dehydrated vegetables, from 8 percent to zero moisture; raw vegetable samples will take 16 hr. These times apply when using an air oven. A more rapid calculation of moisture in dry products can be made by using an infrared moisture tester. The sample must be finely ground so that it passes through a 10 mesh sieve; a given weight is dried out under an infra red lamp, the loss in weight being recorded by a scale on the tester. Results can be obtained in up to 7min, and in as short a period as 4min for some vegetables These moisture testers, however, are not as accurate as the oven-type, and results can vary about 0.5 percent when compared with the latter. It is nevertheless, an indispensable instrument for the shift chargehand to use for rapid tests on material in course of process, particularly for testing products drying in finishing bins, where it is important for the operator to know the drying end-point accurately, before discharging the material to the packing department Sulphur Dioxide Tests for SO2 concentration are carried out by the Monier Williams method,or what was described in the early days of dehydration as the 'Committee method. The former method is rather more accurate but the latter is more generally used with vegetables, for the sake of speed Basically, the calculation is made by boiling a 20g sample of the ground product in dilute hydrochloric acid and titrating iodine into the distillate as ws 250ml of distilled water are placed in a 500ml flask connected by a splash-head to a vertical condenser terminating in a bubbler feeding into 600ml beake 20g of the dried product for analysis are put into the distilled water in
LABORATORY ANALYTICAL TESTS Having received samples representative of a batch of finished product, or incoming raw material, the staff will carry out the following tests: Moisture For moisture tests, either a vacuum oven, set at 70°C, or a fan assisted air oven, set at 10Oo-103"C, is used. The former is more accurate, albeit slower, on account of the low temperature used, as this prevents the charring and burning of the sample when it is completely dried out, and allows a more exact result to be calculated. Samples of raw vegetable should be grated finely before testing, and dry products should be ground in a small coffee grinder. The sample material is dried down to zero moisture, and the loss in weight expressed as a percentage of the original to the nearest 0.1 percent. Two hours is the average time for drying down most dehydrated vegetables, from 8 percent to zero moisture; raw vegetable samples will take 16 hr. These times apply when using an air oven. A more rapid calculation of moisture in dry products can be made by using an infrared moisture tester. The sample must be finely ground so that it passes through a 10 mesh sieve; a given weight is dried out under an infra red lamp, the loss in weight being recorded by a scale on the tester. Results can be obtained in up to 7min, and in as short a period as 4min for some vegetables. These moisture testers, however, are not as accurate as the oven-type, and results can vary about 0.5 percent when compared with the latter. It is, nevertheless, an indispensable instrument for the shift chargehand to use for rapid tests on material in course of process, particularly for testing products drying in finishing bins, where it is important for the operator to know the drying end-point accurately, before discharging the material to the packing department. Sulphur Dioxide Tests for SO, concentration are carried out by the Monier Williams method, or what was described in the early days of dehydration as the 'Committee' method. The former method is rather more accurate but the latter is more generally used with vegetables, for the sake of speed. Basically, the calculation is made by boiling a 20g sample of the ground product in dilute hydrochloric acid and titrating iodine into the distillate as follows: 250ml of distilled water are placed in a 500ml flask connected by a splash-head to a vertical condenser terminating in a bubbler feeding into a 600ml beaker. 20g of the dried product for analysis are put into the distilled water in 234
the flask, with 10ml of concentrated hydrochloric acid. Heat is applied to bring about boiling in 2-3min. The distillate is collected in 200ml of water in the beaker at the bottom of the condenser, and n/100 iodine is titrated from a burette to maintain a slight excess of iodine. A little starch solution indicator is added to the beaker A marked reduction in the rate of evolution of iodine combining substances is taken as the end-point, or when more than one minute is required to decolorise 0. 2mI N/100 iodine. The distillation should be complete in 5-10min Calculations: Iml N/100 iodine titrated =0.32mgm sulphur dioxide Peroxidase Test for Vegetables During blanching, the enzymes present in active form become progressively inactivated by heat. Of these enzymes, the peroxidase complex is readily perceived because of the colour reaction it promotes with a reagent A suitable reagent is a solution of Guaiacol and hydrogen peroxic made as follows: (1)1 per cent w/v Guaiacol dissolved in distilled water )Mix 25ml of 20 volume hydrogen peroxide in 75ml of water, and add 100ml of 1 per cent Guaiacol solution. The sample for analysis is liberally wetted by the above solution, and the development of a brown colour indicates active, or positive, peroxidase. If the colour is not apparent in one minute, the result is negative, and it can be assumed that blanching is adequate If the result is positive, it is necessary to adjust the blanching conditions, either by increase of temperature or product immersion time Blemish Count A limited number of minor blemishes is often permitted, commercially, in dehydrated vegetables but the tolerance must be rigorously controlled Blemish may arise from disease in the fresh vegetable, skin, root or growth defect, or can stem from a processing fault, such as scorching, under or overblanching, or inefficient peeling Obvious blemish should not be present, and the only tolerated blemish is what is described as ', ie, slight blemish in the dry state, which mainly isappears on reconstitution. The standard will obviously vary from processor to processor but, on of dehydrated vegetable. A similar standard applies to meat in a 50g sample average the permitted tolerance is from 5-7 minor blemishes
the flask, with 10ml of concentrated hydrochloric acid. Heat is applied to bring about boiling in 2-3min. The distillate is collected in 200ml of water in the beaker at the bottom of the condenser, and N/100 iodine is titrated from a burette to maintain a slight excess of iodine. A little starch solution indicator is added to the beaker. A marked reduction in the rate of evolution of iodine combining substances is taken as the end-point, or when more than one minute is required to decolorise 0.2ml N/100 iodine. The distillation should be complete in 5-l0min. Calculations: lml N/100 iodine titrated = 0.32mgm sulphur dioxide. Peroxidase Test for Vegetables During blanching, the enzymes present in active form become progressively inactivated by heat. Of these enzymes, the peroxidase complex is readily perceived because of the colour reaction it promotes with a reagent. A suitable reagent is a solution of Guaiacol and hydrogen peroxide made as follows: (1) 1 per cent w/v Guaiacol dissolved in distilled water: (2) Mix 25ml of 20 volume hydrogen peroxide in 75ml of water, and add 100ml of 1 per cent Guaiacol solution. The sample for analysis is liberally wetted by the above solution, and the development of a brown colour indicates active, or positive, peroxidase. If the colour is not apparent in one minute, the result is negative, and it can be assumed that blanching is adequate. If the result is positive, it is necessary to adjust the blanching conditions, either by increase of temperature or product immersion time. Blemish Count A limited number of minor blemishes is often permitted, commercially, in dehydrated vegetables but the tolerance must be rigorously controlled. Blemish may arise from disease in the fresh vegetable, skin, root or growth defect, or can stem from a processing fault, such as scorching, under or overblanching, or inefficient peeling. Obvious blemish should not be present, and the only tolerated blemish is what is described as ‘minor’, ie, slight blemish in the dry state, which mainly disappears on reconstitution. The standard will obviously vary from processor to processor but, on average, the permitted tolerance is from 5-7 minor blemishes in a 50g sample of dehydrated vegetable. A similar standard applies to meats. 235
Reconstitution ratio The dried product must be regularly checked for the reconstitution value, in order that correct cooking instructions can be supplied to the ultimate user. A 50g sample is rehydrated and cooked in the prescribed manner and time. The cooking water is drained off, and the drained weight is calculated against the original dry weight, to give a reconstitution ratio. Culinary Report This test is combined with the previous ratio test, and a system of quality king is implemented and recorded for flavour, texture and colour. The criterion of quality, overall, is that of the freshly cooked fresh vegetable Dried vegetables must not contain bacteria likely to be harmful to man, and the conditions of manufacture must be such that bacterial toxins cannot be formed. General bacterial counts must be low, and it is the microbiologist duty to ensure that factory and personnel hygiene are of a particularly high standard. The use of bactericidal hand creams by operators who handle the raw material- particularly meat and poultry products-is a very essential recaution Bacteriological equipment required for elementary tests will comprise two incubators(maintained at 37 and 55C), a good microscope and an adequate supply of Petri dishes for culturing Meat Product Tests In addition to bacteriological tests, for meat products, there are special required to establish free fatty acids, fat content, peroxide value and salt content Potato Product Tests In addition to the specific tests noted above, for vegetables, tests are made for reducing sugars in raw potatoes and in the dried product in its various forms, and also blue value tests to evaluate free starch Residual Oxygen Test When products are gas packed, tests are made to establish the percentage residual oxygen in the pack, An Orsat apparatus is required for this, and the commercially accepted standard for residual oxygen in a nitrogen-flushed ack is 2 percent or less
Reconstitution Ratio The dried product must be regularly checked for the reconstitution value, in order that correct cooking instructions can be supplied to the ultimate user. A 50g sample is rehydrated and cooked in the prescribed manner and time. The cooking water is drained off, and the drained weight is calculated against the original dry weight, to give a reconstitution ratio. Culinary Report This test is combined with the previous ratio test, and a system of quality marking is implemented and recorded for flavour, texture and colour. The criterion of quality, overall, is that of the freshly cooked fresh vegetable. Bacteriological Tests Dried vegetables must not contain bacteria likely to be harmful to man, and the conditions of manufacture must be such that bacterial toxins cannot be formed. General bacterial counts must be low, and it is the microbiologist’s duty to ensure that factory and personnel hygiene are of a particularly high standard. The use of bactericidal hand creams by operators who handle the raw material - particularly meat and poultry products - is a very essential precaution. Bacteriological equipment required for elementary tests will comprise two incubators (maintained at 37” and 55”C), a good microscope and an adequate supply of Petri dishes for culturing. Meat Product Tests In addition to bacteriological tests, for meat products, there are special tests required to establish free fatty acids, fat content, peroxide value and salt content. Potato Product Tests In addition to the specific tests noted above, for vegetables, tests are made for reducing sugars in raw potatoes and in the dried product in its various forms, and also ‘blue value’ tests to evaluate free starch. Residual Oxygen Test When products are gas packed, tests are made to establish the percentage of residual oxygen in the pack. An Orsat apparatus is required for this, and the commercially accepted standard for residual oxygen in a nitrogen-flushed pack is 2 percent or less. 236
Periodical Tests It is necessary that checks should be made at regular intervals for the presence of arsenic, lead and iron in dehydrated products Metal abrasion is often a source of contamination in a product. This can arise from various items of plant and equipment, hence the necessity for using stainless steel in food handling machinery as far as possible, particularly at the he process. Galvanized iron is sometimes resorted to for equipment in contact with the dry material, mainly on grounds of cost, but this should be kept to a minimum, in view of the contamination risk Arsenic contamination can arise from flue gases, where a direct system of heat is used, but, if proper attention is paid to the use of correct fuels, and the hot air supply is kept clean, this should not give rise to serious problems SPECIFICATIONS Finally, a set of specifications must be established by the technical staff, to cover every product to be handled. It is the duty of the laboratory staff to acquaint production personnel with these specifications, and then evaluate the production samples for compliance Obviously, it is of paramount importance that there is no undue delay in arrying out quality control tests, and it is vital that these run continuously and concurrently with the 24 hour production schedule. Failure to maintain a round-the-clock check can mean considerable quantities of material being turned down as substandard because they do not meet the specification. This can be very costly to the dehydrator, as a salvage operation is not always easy or practicable. Liaison between quality control and production is, therefore, of paramount importance and this cannot be overstressed Bacteriological specifications may well vary, according to the demand of the customer, but the following specification would be generally accepted as the norm Meat Products: Total Count 5000 pet, rom 0.16 Escherichia coli-absent Salmonella species-absent in 25g Vegetables: Total Count,000 per g Maximum Yeast and mould count: 200 per g Bacillus coli-absent from 0. 1g Salmonella species: absent in 25g The complete specification, therefore, will appear under the following headings, against which the Laboratory will report on batch of
Periodical Tests It is necessary that checks should be made at regular intervals for the presence of arsenic, lead and iron in dehydrated products. Metal abrasion is often a source of contamination in a product. This can arise from various items of plant and equipment, hence the necessity for using stainless steel in food handling machinery as far as possible, particularly at the 'wet' end of the process. Galvanized iron is sometimes resorted to for equipment in contact with the dry material, mainly on grounds of cost, but this should be kept to a minimum, in view of the contamination risk. Arsenic contamination can arise from flue gases, where a direct system of heat is used, but, if proper attention is paid to the use of correct fuels, and the hot air supply is kept clean, this should not give rise to serious problems. SPECIFICATIONS Finally, a set of specifications must be established by the technical staff, to cover every product to be handled. It is the duty of the laboratory staff to acquaint production personnel with these specifications, and then evaluate the production samples for compliance. Obviously, it is of paramount importance that there is no undue delay in carrying out quality control tests, and it is vital that these run continuously and concurrently with the 24 hour production schedule. Failure to maintain a round-the-clock check can mean considerable quantities of material being turned down as substandard because they do not meet the specification. This can be very costly to the dehydrator, as a salvage operation is not always easy or practicable. Liaison between quality control and production is, therefore, of paramount importance and this cannot be overstressed. Bacteriological specifications may well vary, according to the demands of the customer, but the following specification would be generally accepted as the norm. Meat Products: Total Count 5000 per g. Escherichia coli - absent from 0.lg. Salmonella species - absent in 25g Total Count - 50,000 per g. Maximum Yeast and mould count: 200 per g. Bacillus coli - absent from 0.lg. Salmonella species: absent in 25g Vegetables: The complete specification, therefore, will appear under the following headings, against which the Laboratory will report on every batch of material: 237
SPECIFICATION Culinary- Colour: Flavour: Texture Blemish per 50g Maximum Minimum Moisture %- Target: Maximum: Minimum Peroxidase: Fat %(Meats) Peroxide Value of extracted fat(Meats) Free Fatty Acids(Meats) Bacteria per g Total Count Escherichia coli Bacillus Coli-Salmonella species Moulds/Yeasts per g: Lead ppm Iron ppm Packing -Residual Oxygen %o Some major buyers of potato granules for use in snack foods require id ditional tests as under as well as those listed above Level of Glycerol monostearate Maximum 1%-typically O6% (2) Tetrasodium pyrophosphate maximum 0. 5%-typically 0. 3% (3)Anti-oxidants(BHA and/or BHT) Maximum 25mg/kg-typically (4)Reducing sugar 2.0% 5)Bulk density 0.9-1.0 g /cc(uncompacted) (6)Rehydration Characteristics Brabender Amylograph units 550-1000 Packaging Specification for potato granules intended for use in value added roducts
SPECIFICATION Culinary- Colour: Flavour: Texture: Blemish per 50g: S02ppm- Target: Maximum: Minimum: Maximum: Minimum: Moisture YO- Target: Peroxidase: Screening: Fat YO (Meats) Peroxide Value of extracted fat (Meats): Free Fatty Acids (Meats): Bacteria per g: Total Count: Escherichia coli: Bacillus Coli-Salmonella species Moulds/Yeasts per g: Arsenic ppm: Lead ppm: Iron ppm: Packing - Residual Oxygen YO: Some major buyers of potato granules for use in snack foods require additional tests as under as well as those listed above: (1) Level of Glycerol monostearate (2) Tetrasodium pyrophosphate (3) Anti-oxidants (BHA and/or BHT) Maximum 1%-typically 0.6% Maximum 0.5Y0-typically 0.3% Maximum 25mg/kg-typically 15-20mg/ kg 0.9 - 1.0 g./cc (uncompacted) Brabender Amylograph units (4) Reducing sugar 2.0% (5) Bulk density (6) Rehydration Characteristics 550-1000 Packaging Specification for potato granules intended for use in value added products. 238
Packaging (Factory) All product packed in drums under nitrogen pending call Drums: Gas tight construction with septum allowing head space analysis. Packed under a nitrogen atmosphere containing a maximum of 2% oxygen Drum to be internally lacquered (Shipping) Sacks: 25kg per sack effectively sealed to pr revent spilla Shelf-life: Drums 12 months Sacks 4 month Holding temperature: Maximum 7"C Laboratory methods for determining moisture, rehydration viscosity, free fatty acids, and reducing sugars are appended in Tables 12.1, 12.2, 12.3 and 12.4 and are extracted from buyers' specifications for bought-in material. Other tests are already outlined in this chapter
Packaging (Factory) All product packed in drums under nitrogen pending calloff. Drums: Gas tight construction with septum allowing head space analysis. Packed under a nitrogen atmosphere containing a maximum of 2% oxygen. Drum to be internally lacquered (Shipping) Sacks: 25kg per sack effectively sealed to prevent spillage. Shelf-life: Drums 12 months. Sacks 4 months. Holding temperature: Maximum 7°C. Laboratory methods for determining moisture, rehydration viscosity, free fatty acids, and reducing sugars are appended in Tables 12.1,12.2,12.3 and 12.4 and are extracted from buyers’ specifications for bought-in material. Other tests are already outlined in this chapter. 239
METHODS OF ANALYSIS MOISTURE IN POTATO GRANULES BY VACUUM I Apparatus Balance accurate to± 25mm Hg or less. pable of maintaining vacuum equivalent to 4. Aluminium moisture dishes, diameter 2-1/2in, height 5/8in. with slip-over cover 5. Gas drying bottle containing concentrated H2SO4 6. Desiccator containing drying agent ( Silica Gel self-indicating) II Method 1. Weigh approximately 2g of potato granules into an aluminium dish previously dried at 98-100"C to constant weight, and cooled to room temperature in a desiccator. Duplicate test 2. Place dishes with cocked lids(do not remove lids) in vacuum oven for 6hr at 70'C under vacuum equivalent to 25mm of mercury. When the correct vacuum pressure is obtained, the time interval of 6hr is then begun. At this time, air at the rate of 2 bubbles per second is allowed to enter the vacuum oven through a sulphuric acid drying bottle. 25mm of mercury means that the internal pressure in the vacuum oven will be 5mm of mercury above perfect vacuum 3. Remove the dishes after tightening their covers. Transfer to the desiccator, and allow to cool to ambient temperature Ilo 4. approximately 10-15min)before weighing Calculate the moisture Loss in weight x 100 1. Moisture le weight 2. Duplicate samples should be within+0.1% moisture
METHODS OF ANALYSIS MOISTURE IN POTATO GRANULES BY VACUUM OVEN I Apparatus 1. 2. Vacuum oven. 3. 4. 5. 6. Balance accurate to f 0.001g. Vacuum pump capable of maintaining vacuum equivalent to 25mm Hg or less. Aluminium moisture dishes, diameter 2-1 /2in., height 5/8in., with slip-over cover. Gas drying bottle containing concentrated H,SO,. Desiccator containing drying agent. (Silica Gel self-indicating). I1 Method 1. Weigh approximately 2g of potato granules into an aluminium dish previously dried at 98"-100"C to constant weight, and cooled to room temperature in a desiccator. Duplicate test. Place dishes with cocked lids (do not remove lids) in vacuum oven for 6hr at 70°C under vacuum equivalent to 25mm of mercury. When the correct vacuum pressure is obtained, the time interval of 6hr is then begun. At this time, air at the rate of 2 bubbles per second is allowed to enter the vacuum oven through a sulphuric acid drying bottle. 25mm of mercury means that the internal pressure in the vacuum oven will be 5mm of mercury above perfect vacuum. Remove the dishes after tightening their covers. Transfer to the desiccator, and allow to cool to ambient temperature (approximately 10-15min) before weighing. 2. 3. 4. Calculate the moisture. I11 Calculations Loss in weight x 100 sample weight 1. % Moisture = 2. Duplicate samples should be within 5 0.1% moisture - *^
EVALUATION OF POTATO GRANULE REHYDRATION CHARACTERISTICS USING THE BRABENDER VISCOGRAPH (VARIABLE SPEED)(COLD METHOD) I Apparatus 1. Brabender Viscograph, A. Set at 75r B Fitted with a 2000cm per g sensitivity cartridge. 500ml graduated cylinder 3. Balance capable of weighing + Olgram Il Calibration and Checkout Procedures 1. Once per day the d the bowl should be checked with a gauge. A Insert gauge into bowl. The pins should be so aligned as to go through the holes in the gauge. Note: Mis-alignment is noted by a clicking sound B. The pins on the stirrer should also be aligned with the gauge 2. If the sensitivity is changed, zero the instrument as follows Place 500ml cold distilled water into bowl B. Turn on the machine as noted in 111.1 and 111.7 C. Loosen sensitivity cartridge lock nuts and turn the head until the pen reads zero without using any added weights D. Tighten lock nuts while holding the sensitivity cartridge so that the Pen Is on zero. E. Run for approximately 5min to ensure the pen is on zero III Procedure 1. Turn water and power on 2. Set thermoregulator transport in centre position. ( Leave in this position 3. Put the toggle switch under coding heading into the (Fast Uncontrolled) position 4. Check to make sure pen is working and set at zero 5. Place the cleaned mixing bowl into position and add 400ml of distilled water at4°C. 6. Add 100g of potato granules and stir vigorously to wet all granules 7. Within 30sec lower stirrer and lock pin in place. Then press red button to start 8. Timer should be set for 10min 9. Lower cooling probe 10. The answer is reported by taking the chart reading after 10min
EVALUATION OF POTATO GRANULE REHYDRATION CHARACTERISTICS USING THE BRABENDER VISCOGRAPH (VARIABLE SPEED) (COLD METHOD) I Apparatus 1. Brabender Viscograph, A. Set at 75rpm B. Fitted with a 2000cm per g sensitivity cartridge. 2. 500ml graduated cylinder. 3. Balance capable of weighing f 0.lgram. I1 Calibration and Checkout Procedures 1. Once per day the stirrer and the bowl should be checked with a gauge. A. Insert gauge into bowl. The pins should be so aligned as to go through the holes in the gauge. Note: Mis-alignment is noted by a clicking sound. B. The pins on the stirrer should also be aligned with the gauge. 2. If the sensitivity is changed, zero the instrument as follows: A. Place 500ml cold distilled water into bowl. B. Turn on the machine as noted in 111.1 and 111.7. C. Loosen sensitivity cartridge lock nuts and turn the head until the pen reads zero without using any added weights. D. Tighten lock nuts while holding the sensitivity cartridge so that the pen is on zero. E. Run for approximately 5min to ensure the pen is on zero. 111 Procedure 1. Turn water and power on. 2. Set thermoregulator transport in centre position. (Leave in this position). 3. Put the toggle switch under coding heading into the (Fast Uncontrolled) position. 4. Check to make sure pen is working and set at zero. 5. Place the cleaned mixing bowl into position and add 400ml of distilled water at 4°C. 6. Add lOOg of potato granules and stir vigorously to wet all granules. 7. Within 30sec lower stirrer and lock pin in place. Then press red button to start. 8. Timer should be set for 10min. 9. Lower cooling probe. 10. The answer is reported by taking the chart reading after l0min. 24 I
DETERMINATION OF CHLOROFORM EXTRACTABLE FATTY SUBSTANCES IN POTATO GRANULES Whatman Extraction Thimble 30mm by 100mm (41 by 123mm) Analytical Balance Cotton Wool Quickfit Round Bottom Flask 250ml (500ml) Soxhlet extractor Soxhlet Condenser Isomantle Drying Oven100℃ Desiccator Desiccant Reagents Petroleum Spirit(40"-60C) Method Leigh accurately, approximately 20g (50g) sample into an extraction thimble 30 by 100mm(41 by 123mm) 2. Plug with wad of cotton wool (fat-free) 3. Weigh accurately a clean dry 250ml (550ml) Round Bottom Flask. 4. Pour 150ml (300ml)Petroleum Spirit into the flask 5. Place the thimble containing the sample into a Soxhlet extractor 6. Connect the Soxhlet extractor to the flask and a condenser. 7. Place in an isomantle 8. Extract for at least 4hr. 9. Distil off Petroleum Spirit 10. Place the flask in the drying oven for 1hr. 11. Remove and place in the desiccator to cool 12. Reweigh the flask Calculation Extractable Fat Increase in weight of flask x 100 Weight of Sample
DETERMINATION OF CHLOROFORM EXTRACTABLE FATTY SUBSTANCES IN POTATO GRANULES Apparatus Whatman Extraction Thimble 30mm by 100mm (41 by 123mm) Analytical Balance Cotton Wool Quickfit Round Bottom Flask 250ml. (500ml). Soxhlet Extractor Soxhlet Condenser Isomantle Drying Oven 100°C Desiccator & Desiccant Reagents Petroleum Spirit (40" - 60°C). Method 1. Weigh accurately, approximately 20g (50g) sample into an extraction thimble 30 by lOOmm (41 by 123mm). 2. Plug with wad of cotton wool (fat-free). 3. Weigh accurately a clean dry 250ml(550ml) Round Bottom Flask. 4. Pour 150ml (300ml) Petroleum Spirit into the flask. 5. Place the thimble containing the sample into a Soxhlet extractor. 6. Connect the Soxhlet extractor to the flask. and a condenser. 7. Place in an Isomantle. 8. Extract for at least 4hr. 9. Distil off Petroleum Spirit. 10. Place the flask in the drying oven for lhr. 11. Remove and place in the desiccator to cool. 12. Reweigh the flask. Calculation Increase in weight of flask x 100 Weight of Sample % = Extractable Fat = 242
